In the above discussion, we concluded that Notch signaling, including ligands (e.g., Jagged1, Dll1, and Dll4), receptors (e.g., Notch1, Notch2), and downstream utility molecules (e.g., RBP-J, Hes1), is directly involved in the regulation of immune cells’ anti- or pro-tumor immune responses in various ways. The gene discussed is DLL4; the disease is neoplasm.